Renin-angiotensin system gene polymorphisms: assessment of the risk of coronary heart disease.

BACKGROUND: Renin-angiotensin system genes are candidate genes in cardiovascular system diseases. Angiotensinconverting enzyme (ACE), angiotensinogen (AGT) and angiotensin II type 1 receptor (AT1R) gene polymorphisms are considered risk factors in coronary heart disease (CHD). AIM: To evaluate the involvement of the ACE, AGT and AT1R genetic variants in predisposition to CHD as well as their association with other known risk factors. METHODS: The study included 400 male subjects (200 with CHD and 200 healthy individuals). Genotypes were determined by a polymerase chain reaction (PCR). For the AGT and AT1R genes a restriction analysis of the PCR product was performed. The allele frequency and genotype distribution were compared between groups. RESULTS: The allele and genotype frequencies of the ACE gene were similar in both groups, however, a significantly higher frequency of the DD genotype was observed in the presence of hyperlipidemia (39% vs 24% in non-hyperlipidemic subjects, p<0.01). The AGT gene polymorphism was associated with the development of CHD. The T allele was significantly more frequent in patients than in the control group (55% vs 44%, p<0.05). The heterozygous MT genotype was observed in 61% of patients compared to 40% in the controls (p<0.05). The A1166C polymorphism of the AT1R gene was also associated with CHD as well as with age at the onset of disease. The frequency of the C allele was 29% compared to 21% in the control group (p<0.01) and the frequency of the CC homozygote was almost three times higher in patients. CONCLUSIONS: There is an association between molecular variants of the angiotensinogen and angiotensin II type 1 receptor and increased risk of CHD. The DD genotype of the ACE gene polymorphism and the TT genotype of the AGT gene polymorphism were significantly more frequent in patients with hyperlipidemia. The TT genotype of the AGT gene M235T polymorphism was associated with an increased risk of CHD and myocardial infarction only in smokers.

Searching for a better assessment of the individual coronary risk profile. The role of angiotensin-converting enzyme, angiotensin II type 1 receptor and angiotensinogen gene polymorphisms.

BACKGROUND: Polymorphisms within renin angiotensin system genes have been investigated as risk factors for coronary artery disease in different populations with contradicting results. The aim of this study was to investigate the genotype distribution and the allele frequencies of ACE, AT1R and AGT gene polymorphisms as coronary artery disease factors and their synergistic effects on coronary risk in an Italian population. METHODS AND RESULTDS: In this study ACE, AT1R and AGT gene polymorphisms were investigated in 205 consecutive coronary artery disease patients and in 209 controls. These polymorphisms were analysed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). The ACE D and AGT 235T allele, but not AT1R C allele, frequency was statistically significant in patients. An association between coronary artery disease and ACE DD, AT1R CC and AGT TT genotype, was found by univariate analysis (OR 2.06 P=0.0007, OR 2.49 P=0.009, OR 1.87 P=0. 019, respectively). At multivariate analysis ACE DD and AT1R CC genotype (OR 1.81 P=0.011, OR 2.61 P=0.011, respectively) remained associated with coronary heart disease. Subjects carrying the ACE DD genotype and AT1R C allele showed a stronger association with myocardial infarction (OR=4.02, P<0.0001). CONCLUSION: Our report indicates the increased risk of coronary artery disease in the presence of ACE DD and AT1R CC genotypes independent of other risk factors, in Italian patients. The present study stresses the relevance of screening for genetic risk factors.

Reduced atrial angiotensin receptor type 1 mRNA content in end-stage human heart failure: assessment by a novel quantitative PCR-ELISA technique.

The number of atrial angiotensin II binding sites is reduced in end-stage human heart failure. The goals of our study were the development of a quantitative polymerase chain reaction for angiotensin II receptor type 1 mRNA to determine the angiotensin receptor type 1 (AT1) mRNA content in the atria of patients with end-stage heart failure. We established a quantitative PCR based on coamplification of AT1 wild-type and an internal standard in the same PCR, followed by liquid-phase hybridization of PCR products in microtiter plates and quantitation by ELISA. Glyceraldehyde phosphate dehydrogenase mRNA in the same samples was used to relate the AT1 mRNA content to a stably expressed reference gene. Atrial samples from 11 patients with end-stage heart failure obtained at cardiac transplantation were compared with atrial samples from 11 patients with normal cardiac function undergoing routine cardiac surgery. A PCR/ELISA system with a variance of about 6% after reverse transcription and a linear measuring range was established. In the samples from 11 patients with end-stage heart failure a 58% decrease in AT1 mRNA content was found in comparison with 11 controls (heart failure: 185,680 +/- 196,912 AT1 mRNA copies/microgram RNA, controls: 440,555 +/- 268,456, P < 0.02). When AT1 mRNA content was related to glyceraldehyde phosphate dehydrogenase mRNA, a 65% decrease was detected (AT1/glyceraldehyde phosphate dehydrogenase: heart failure: 4.84 +/- 5.18; controls: 13.74 +/- 7.77; P < 0.005). Standardization of PCR resulting in a low coefficient of variance, high reproducibility, and large sample capacity is possible using optimal internal standardization and the liquid-phase hybridization/ELISA system for detection. The optimized PCR procedure indicated downregulation of atrial AT1 in end-stage human heart failure, suggesting a reduced capacity of the atria to respond to angiotensin II stimulation in end-stage heart failure.